In a packet transport network, as shown in FIG. 1, a procedure of establishing a label switched path is that, a source node sends a Path message (connection establishment request message) hop-by-hop to a sink node, where the Path message carries bandwidth request information; after receiving the bandwidth information, each intermediate node on the way completes reserving a bandwidth resource, and allocates the bandwidth resource to a link; after receiving the Path message, the sink node returns a message (connection establishment request response message), and finally a label path is successfully established between the source node and the sink node.
With the development of communications technologies, the intermediate node in the packet transport network may be a fiber node, and may also be or a microwave node. One important characteristic of the microwave node is adaptive modulation, which may adjust a modulation manner of a transmit signal according to an external environment, so as to maintain a high link usability, that is, bandwidth of the microwave node is changeable, and has a maximum value and a minimum value. In the prior art, after receiving the Path message sent by the source node, the microwave node may reserve bandwidth for this Path request when the bandwidth is at the minimum value, so as to maintain the high link usability.
After analysis of the prior art, the inventor finds that the prior art has at least the following defects. Because the bandwidth of the microwave node changes in a range, if it is computed when the bandwidth is at the minimum value, the bandwidth resource may not be allocated in most cases, which is a waste of the bandwidth resource. Moreover, if the bandwidth information carried in the Path message is greater than the minimum bandwidth of a microwave link, the microwave node may refuse to establish the link, so that the label switched path cannot be established on this node. For example, minimum bandwidth of one microwave link is 50 Mbps and maximum bandwidth of it is 400 Mbps due to a reason of the adaptive modulation, and assume that the bandwidth request information carried in the Path message sent by an initiating end (source node) when establishing the label switched path is 60 Mbps, if the microwave node reserves the bandwidth information for the path request according to the minimum bandwidth resource of 50 Mbps, the path cannot be established, while in fact a large quantity of bandwidth resources are left idle.